TO COMPARE THE NUMBER OF APHERESES REQUIRED TO HARVEST AT LEAST 5 X 10(6) CD34+ CELLS/KG ACTUAL BODY WEIGHT USING EITHER HUMAN STEM CELL FACTOR IN COMBINATION WITH FILGRASTIM OR FILGRASTIM ALONE FOR MOBILIZATION OF PROGENITOR CELLS IN PATIENTS WITH HIGH RISK STAGE II , STAGE III, OR STAGE IV BREAST CANCER. TO ASSESS THE SAFETY OF HUMAN STEM CELL FACTOR WHEN ADMINISTERED IN COMBINATION WIT H FILGRASTIM, INCLUDING THE EVALUATION OF TUMOR CELL CONTAMINATION OF THE LEUKAPHERESIS PRODUCTS.